Assessment of the utility of obtaining human profiles from drug seizures

Monograph no. 42

The majority of drugs in seizures were found to contain human DNA which rarely came from a single individual. Attempts to resolve mixed STR profiles of DNA extracted from drug seizures was ineffective as the ratio of individual alleles is not preserved during amplification and varies from locus to locus. However, hypervariable sequences in mitochondrial DNA provide a means of determining the number of contributors to a sample and gaining information which allows tactical comparison of seizures with the possibility of identifying individuals situated higher up the distribution chain. Methods for reliable extraction of DNA from seizures are described and two methods for resolution of mixed mitochondrial sequences presented: by cloning and also by next generation sequencing, a cloning free method that is more suitable for forensic purposes.